The prior art is replete with a wide variety of different approaches to conditioning air to improve livability within an enclosed space in both the air conditioning, or cooling, mode.
The evaporator configuration of this invention consists of a planar coil bent into an arcuate shape, as by bending about a right angle axis. It will be referred to herein as the "O-coil." The O-coil arrangement was designed to replace the commercially most successful A-type coil in which slab heat exchangers are placed at respective angles with end gables to cause air to flow through the heat exchange coils in an evaporator set up, as for cooling and/or dehumidifying air. It is in this environment that the invention will be described and claimed hereinafter. It is in this comparison that the invention will be more nearly completely understood by referring to FIG. 15 and Table I later hereinafter.
In addition, one of the more pertinent patents found in a prior search, and described in the enclosed 37 CFR 1.56(a) Information Disclosure Statement, accompanying this application, U.S. Pat. No. 1,994,184 to Williams which describes a warm air heating system that is adaptable for use with a fuel burner and can be employed to provide distribution means for distributing hot water for domestic purposes. In addition, the invention describes a method of cooling the atmosphere of rooms by circulating refrigerated water through a coil of pipes installed into the main trunk of an air duct system. While this invention could not be employed in applicant's invention, it is pertinent in showing a central distribution system for distributing air cooled by refrigerated water circulated through the coil of pipes installed into the main trunk of air duct system and remote from and dependent on a separate blower for airflow. However, the invention does not anticipate reducing the temperature of the coil of pipes down to dew point made obvious by the absence of condensate collection means for the collection and removal of condensate or humidity.
A consideration of the total prior art shows that none of the prior art could be employed in applicant's invention and that the prior art does not anticipate or make obvious applicant's invention. In particular, the prior art tends to employ fans for moving air in which the fans are located as a part of the evaporator so that higher differential pressures can be employed. Moreover, most of the prior art was employed for merely local, or spot, cooling and could not be employed in a central distribution system, particularly where a duct system was employed in having a blower elsewhere, or remote from the O-coil of this invention.
It is desirable that the invention have the following features not provided heretofore.
1. The invention should not include an air mover as a part of the design, since if a fan is employed, a simple change of direction such as changing the angle to increase the pitch for more air flow, changes the direction of the air flow.
2. It is important that the invention be compatible in retrofit, or new construction situations with any available residential or light commercial air handler or furnace regardless of direction of air flow and either upstream or downstream of the air mover.
3. It is advantageous that the invention be installable in a retrofit situation even in small spaces without requiring removing any door or requiring any doorway disassembly.
4. It is beneficial that the invention include the housing as an integral part of the assembly. Not only does the dimension of the housing affect the coil performance, it must mate with the openings of conventional systems such as a retrofit installation, in a ducted system, opening of furnaces or the like and be adapted to handle the air volume of either light commercial or residential application, yet assure that the effort to install the coil and the housing is no greater than would be encountered when installing a conventional indoor coil assembly.
5. It is important that the invention achieve a designed air distribution with critical volume ratios with respect to volume of the coil and the volume of the housing. Where the heights of the coil and housing are equal, the critical volume ratios become critical area ratios. The coil housing not only serves as an enclosure to insulate and direct the conditioned air in accordance with entering effluent air circulated within a distribution duct, it also serves to direct the air through the coil surface by controlling resistance effected by the air flow. In the conventional installation, the pressure across the coil may be high enough to effect a distribution of the air flow according to a desired plan. In this invention, however, which uses only a primary coil, or single tube row in most instances or at most a portion of an additional tube row, the pressure drop is so low that means to affect the air flow is frequently employed to assist in achieving the desired air distribution of flow. In one instance, the item affecting flow of air is the critical ratio of the cross-sectional area of the housing, to the cross-sectional area of the coil.
6. It is desirable that this invention be efficient in transferring heat; for example, it can employ a high efficiency tubing such as rifled tubing and enhanced plate fins to achieve heat transfer higher than possible heretofore in order to achieve the heat transfer per unit of space occupied.
7. This invention will make cost savings possible and achieve ready commercial acceptance. To do this, the O-coil configuration of this invention achieves a labor savings in excess of 30 percent. It enables making a single installation of inlet and outlet headers with a pressure test before being bent into arcuate configuration, rather than requiring two separate tests. Additional features include:
a. when compared to its closest commercially viable design, that is the multirow A-coil, the present invention requires only a single coil manufacture whereas the A-coil requires two. Most of the arguments presented with respect to the A-coil are valid with respect to any multi-row coil. PA1 b. This single-row O-coil configuration is referred to as an O-coil and it eliminates the triangular delta plates that must be installed on both ends of an A-coil; PA1 c. the O-coil has less weld joints per unit when compared to the A-coil and is adapted for either up flow or down flow of the air to achieve high efficiency heat transfer; PA1 d. the A-coil slabs, which consist of two separate coil assemblies, must be manifolded together whereas the O-coil is one complete coil and is manufactured in a single operation without requiring manifolding together the separate slabs or the like; and PA1 e. finally, the A-coil slabs must be manually assembled and fastened into one assembly; whereas the O-coil is inherently a single assembly that is mechanically formed into an assembly and can be installed readily.
From the foregoing it can be seen that this invention provides improvements not seen in the prior art. For example, when compared with the A-coil, the O-coil manufacture increases the face area by more than about 40 percent for a given volume so that it employs less copper in the heat exchanger; requires less horse power to flow air through the heat exchanger; requires less material; eliminates weight; reduces the number of U-bends and refrigerant crossover tubing, reducing soldering leak possibilities, as well as reducing work in assembly.
By doing this with the higher performance coil designs available today, the unit is designed to serve as direct replacement for the conventional A-coil units at approximately 70 percent of the cost. Laboratory testing performed to demonstrate the feasibility of this invention have demonstrated this to be the case.
These features have not been satisfactorily provided by the prior art heretofore.